The present invention relates generally to accessories for use with optical lensmeters in the measurement of optical properties of a lens, and more particularly to lensmeter accessories for supporting and positioning a corneal contact lens on a light path of a lensmeter.
Lensmeters typically include a lens platform for supporting a spectacle or eyeglass lens with its vertex point against a lens stop of the lensmeter in alignment with a light path of the lensmeter. Such lensmeters may also be used to measure the optical properties of a contact lens, however this requires that the contact lens somehow be held against the lens stop in alignment with the light path. The task of supporting and positioning a contact lens in the light path is problematic because contact lenses are difficult to handle and easy to drop, scratch, or lose.
Prior art schemes for holding a contact lens against a lensmeter lens stop in alignment with a light path of the lensmeter include using adhesives and providing the lensmeter with a generally vertical light path to enable the contact lens to rest on the lens stop by gravity.
A lensmeter accessory available for use with the Model 70 Vertometer lensmeter manufactured by Leica Inc., owner of the present application, includes a small tube having glass insert of special index which moves the focal plane of the lensmeter objective lens forward for purposes of testing a contact lens. A first end of the tube is insertable in an aperture of the lens stop and a second end of the tube comprises a spherical surface for engagement with a concave surface of the contact lens for holding the contact lens in place along the lensmeter light path.
A more recent lensmeter developed by Leica Inc., which is the subject of copending U.S. Des. patent application Ser. No. 29/031,945, has a substantially horizontal light path and a vertically adjustable lens platform. The above mentioned prior art schemes for holding a contact lens are not suited for use with the newer lensmeter.